Methods for operating and controlling an internal combustion engine that exhausts no gas into outside atmosphere

ABSTRACT

An internal combustion engine inducts no air from outside atmosphere and it discharges no gas into outside environment. The engine receives hydrocarbon fuel and oxygen, and its combustion gas consists mostly of carbon dioxide and water vapor. Carbon dioxide is captured, stored and subsequently sequestered by using it with water to create a hydrocarbon fuel that can be supplied back to the engine. In that way, the engine fuel is repeatedly regenerated and reused, and the engine operates in a carbon neutral mode of operation. Some of the combustion gas is used as a diluent gas in the engine. High specific heat and high density of that gas permit operation in high-efficiency overexpanded cycle without an increase in the engine size. Various methods of the engine control and operation are described, including methods to reduce pumping loss. Various modes of in-cylinder diluent gas formation are considered.

FIELD OF THE INVENTION

The present invention relates to methods of operation of internalcombustion engines that don't induct air from outside atmosphere anddischarge no gas into the atmosphere.

BACKGROUND OF THE INVENTION

The airless engine of the present invention inducts no air from outsideatmosphere and discharges no gas into the atmosphere, thus contributingto better air quality and reduced global warming. That engine also hassome unique properties that can be exploited to design and operate theengine using methods that permit the airless engine to achieve a muchhigher efficiency than in a conventional air-inducting engine. Thesemethods include:

-   -   1. Increasing the expansion ratio.    -   2. Elimination of throttling.    -   3. Recovery of lost heat.    -   4. Reducing friction.

The present invention also includes the method of minimizing the volumeof gas storage and the method of sequestering the carbon dioxide,produced in combustion, by converting it into fuel to power the engine.

These methods are the subject of the present invention.

PRIOR ART

A U.S. Pat. No. 8,151,553 to Schechter describes an internal combustionengine that inducts no air from outside atmosphere and exhausts no gasinto the atmosphere. It receives fuel and oxygen, performs a combustioncycle and most of its combustion gas is recycled back into the engine,where it serves as a diluent gas. It is an airless engine.

Thanks to higher density and higher specific heat of the diluent gas, anairless engine requires a smaller volume of diluent gas than anair-inducting engine of equal power. The method used in the systemdescribed in the above patent uses the above properties of the diluentgas to reduce the size of the engine. A smaller engine has lessfriction, which improves its efficiency.

In the airless engine of the present invention, an increase in theengine efficiency is achieved in a different way: The timing of theengine intake valves closing is such that the volume of gas trapped inthe cylinder at the beginning of compression is only a fraction of thecylinder volume. The clearance volume is reduced too, so that a propervalue of compression ratio is retained. Reduction in clearance volumeleads to an increase in expansion ratio, which is achieved without anincrease in cylinder volume. The increase in expansion ratio improvesthe efficiency of the thermodynamic cycle.

An increase in expansion ratio can also be accomplished in aconventional air-inducting engine. Such a cycle is often calledoverexpanding cycle, or Atkinson cycle. However, in case of theconventional engine, an increase in expansion requires an increase inthe cylinder volume, which leads to an increase in friction. Thanks tohigher density and higher specific heat of the gas, an increase inexpansion, in the airless engine, is achieved without increasing thecylinder volume.

An internal combustion engine operates under load most of the time. Insuch operation, a loss to friction is a small fraction of the workperformed, while a substantial increase in expansion rate can do evenmore for improvement in efficiency than a reduction in engine size.Therefore the method of the present invention offers a greaterimprovement in engine efficiency in most cases.

The above patent describes using a controllably variable restriction tothe flow of excess gas in order to control the pressure of recycledcombustion gas. Using a restriction to gas flow involves a pumping lossleading to reduction in efficiency.

In the system of the present invention, restriction to the flow of gasis avoided. Instead, the excess gas flows into a constant-displacementcompressor that operates with a speed proportional to the speed of theengine. Since the compressor displacement is fixed, and the compressorinlet gas temperature is approximately constant, any change in the massof compressor inlet flow per cycle must be associated with aproportional change in its pressure, which is equal to the pressure ofthe engine diluent gas. Therefore the mass of the diluent gas in theengine automatically varies in proportion to changes in the fuel flow.The system is inherently self-regulating, and the mass of the diluentgas automatically changes in proportion to the changes in the mass flowof the fuel received into the engine. The gas-to-fuel ratio remainsconstant, and there is no need for throttling to control the flow of theinducted diluent gas. This reduces the pumping loss and contributes tobetter fuel efficiency.

The above patent describes application of an outside heat exchangerusing the heat of the recycled gas to boil water and adding theresulting steam to the cylinder chamber during gas expansion, thus usingthe heat of the hot recycled gas to increase efficiency. An outside heatexchanger is a relatively inefficient device: only some of the gas heatis transferred to the water. Some heat, inevitably, escapes to theoutside environment, and only a fraction of the heat escaping with theexhaust gas is recovered.

In contrast to the above, in the system of the present invention, theengine can induct hot exhaust gas. Water is injected directly into thecylinder, forming steam there that performs useful work, thus improvingthe efficiency of the engine. Without the outside heat exchanger, therecovery of the exhaust gas energy is more complete, which results ingreater improvement in efficiency then in the system of the abovepatent. Elimination of the heat exchanger is also a reduction in costs.

The system of the present invention anticipates hot gas induction inboth four-stroke and two-stroke cycles. Operation in two-stroke cycle,with hot gas induction, reduces the size of the engine, which reducesthe friction and improves the engine efficiency. The above patent doesnot anticipate such operation.

The system of the above patent anticipates adding water to the cylinderchamber, during gas compression, to reduce the work of compression andimprove efficiency. The system of the present invention also anticipatesadding water to the engine to reduce the work of compression and improvethe efficiency.

The system of the present invention anticipates the method of minimizingthe required volume of gas storage, which can be accomplished bysequentially storing the oxygen and the carbon dioxide in the samecontainer. The above patent does not anticipate such method ofoperation.

The system of the present invention anticipates converting carbondioxide, produced in engine combustion, into fuel that is used to powerthe engine. The above patent does not anticipate such operation.

A U.S. Pat. No. 7,954,478 to Schechter describes an internal combustionengine using some of its exhaust gas mixed with oxygen instead of air.Nitrogen oxide emission is eliminated, but carbon dioxide created incombustion is discharged into environment.

A U.S. Pat. No. 7,958,872 to Schechter describes an internal combustionengine that is similar to the engine of the above U.S. Pat. No.7,954,478, but it also includes collecting water produced in combustionand injecting it back into the engine. Water evaporation in the engineimproves fuel economy. Carbon dioxide created in combustion isdischarged into environment.

A U.S. Pat. No. 8,046,984 to Schechter describes a gas turbine engineusing some of its exhaust gas mixed with oxygen instead of air. Nitrogenoxide emission is eliminated, but carbon dioxide created in combustionis discharged into environment.

OBJECTS AND ADVANTAGES

One object of the present invention is to improve the efficiency of thethermodynamic cycle in the airless engine of the present inventionrelative to thermodynamic efficiency of a conventional air-inductingengine of equal power. This is accomplished by increasing the expansionof gas in the cylinder of the airless engine, without increasing the gascompression and without an increase in the cylinder volume. The timingof the intake valves is such that the gas contained in the cylinderchamber at the beginning of gas compression occupies only a fraction ofthe full cylinder volume, and the gas compression takes up only afraction of the piston stroke, while the gas expansion takes up theentire piston stroke. The clearance volume is reduced too, so that adesirable value of compression ratio is retained. Reduction in theclearance volume increases the expansion ratio, which remainssubstantially greater than the compression ratio, thus improving theengine efficiency. An increase in efficiency is achieved withoutincrease in cylinder volume.

Another object of the present invention is to improve the efficiency ofthe airless engine by eliminating the need to use throttling to controlthe flow of the inducted gas. This is accomplished by the excess gasflowing into a constant displacement compressor that operates with aspeed proportional to the speed of the engine. Since the compressordisplacement is fixed, and the compressor inlet gas temperature isapproximately constant, any change in the mass of compressor inlet flowper cycle must be associated with a proportional change in its pressure,which is equal to the pressure of the engine diluent gas. Therefore themass of the diluent gas in the engine automatically varies in proportionto changes in the fuel flow. The system is inherently self-regulating,and the mass of the diluent gas automatically changes in proportion tothe changes in the mass flow of the fuel received into the engine. Thegas-to-fuel ratio remains constant, and there is no need for throttlingto control the flow of the inducted (or retained) diluent gas. Thisreduces the pumping loss and contributes to better fuel efficiency.

Still another object of the present invention is to improve theefficiency of the airless engine by eliminating outside cooling of therecirculated gas and injecting water for in-cylinder cooling. Bringingback hot gas brings back to the cylinder some of the heat that escapedfrom the cylinder previously. That heat adds to the heat of combustionand compensates for some of the heat that escaped with exhaust gas andwith the coolant. The result is a net reduction in heat loss during thecycle.

One more object of the present invention is to improve the efficiency ofthe airless engine by completing the cycle in two piston strokes,instead of four, which reduces the amount of friction work associatedwith the piston rubbing against the walls of the cylinder. This improvesthe efficiency.

Yet another object of the present invention is to reduce the structuralcomplexity of the airless engine by integrating the exhaust manifoldwith the cylinder head, and using only one type of valve that remainsopen continuously during exhaust and intake strokes of the piston.

Another object of the present invention is to minimize the volume of therequired gas storage by sequentially storing the oxygen and the carbondioxide in the same container.

One more object of the present invention is to use sequestration ofcarbon dioxide, produced in the engine combustion, to convert it intohydrocarbon fuel to be used to power the engine.

Further objects and advantages of our invention will become apparentfrom a consideration of the drawings and ensuing description.

SUMMARY

The airless engine of the present invention is a piston-type internalcombustion engine that inducts no air from outside atmosphere andexhausts no gas to outside atmosphere. Some of the exhaust gas isreturned to (or retain in) the cylinder, where it serves as a diluentgas. That gas may be cooled before return to the engine. Each cylinderof the engine contains diluent gas that contains mostly carbon dioxideand water vapor. Each cylinder repeatedly receives fuel and oxygen andrepeatedly performs a combustion cycle, in which fuel and oxygen areconverted into carbon dioxide and water vapor. Water vapor is condensedand disposed of. Carbon dioxide is collected, stored and subsequentlyremoved for longer term storage and sequestration.

One of the most important parameters of any internal combustion engineis its efficiency, which is determined by the ratio of useful workperformed by the energy released in combustion. During gas expansion,some of that energy is transferred from the gas to the piston thatperforms the useful work, but a substantial part of that energy iscarried out with the exhaust gas and the engine coolant, and serves nouseful purpose. The main reasons for those losses are:

-   -   1. Insufficient gas expansion.    -   2. Pumping loss due to throttling.    -   3. Loss of heat to coolant and exhaust gas.    -   4. Mechanical friction.

The airless engine of the present invention can be designed and operatedusing methods that lead to reduction or elimination of the above energylosses, thus improving the engine efficiency. These methods involve thefollowing:

-   -   1. Increasing the expansion ratio.    -   2. Elimination of throttling.    -   3. Recovery of lost heat.    -   4. Reducing friction.    -   5. Varying valve timing.

The present invention also includes the method of minimizing the volumeof gas storage and the method of sequestering the carbon dioxide,produced in combustion, by converting it into fuel to power the engine.Carbon dioxide is captured, stored and subsequently sequestered by usingit with water to create a hydrocarbon fuel that can be supplied back tothe engine. In that way, the engine fuel is repeatedly regenerated andreused, and no additional fuel is required.

These methods are the subject of the present invention and are describedbelow.

Increasing Expansion Ratio

Increasing the gas expansion increases the fraction of the gas energytransferred to the piston, thus improving the efficiency. However,increasing the gas expansion is limited by the fact that, in mostengines, the expansion ratio is about equal to the compression ratio,which cannot be increased due to limitations in peak pressure andtemperature in the engine. This, however, does not apply to enginesoperating in an overexpanded cycle (sometimes referred to as Atkinsoncycle).

In an engine operating in overexpanded cycle, the expansion ratio isinherently much greater than the compression ratio, and this permits toachieve a much better efficiency. Practically, this is often achieved bythe engine cylinder having a larger volume, with a longer piston stroke,than in a conventional engine of the same power. The longer strokeprovides for greater expansion ratio, while the compression ratio andthe inducted gas volume remain the same as in the above conventionalengine.

A major disadvantage of the above method is a significant reduction inpower density, because of the increase in engine volume. Thisdisadvantage can be eliminated in an airless engine by modifying theengine and its operation as described in the present invention. Suchengine can take full advantage of the significant improvement inefficiency, associated with the overexpanded cycle, and still deliverthe same power as a conventional engine of equal cylinder volume. Thereis no reduction in power density.

An airless engine inducts no air from outside atmosphere and dischargesno gas into the atmosphere. Most of its combustion gas is retained in orreturned back into the engine cylinders, where it serves as a diluentgas. Fuel and oxygen are added to the diluent gas, and the mixture isused to perform combustion.

In a conventional air-inducting internal combustion engine, the gascontained in the cylinder is mostly nitrogen. In an airless engine, thecylinder gas is mostly carbon dioxide and water vapor, and the specificheat and density of that gas are substantially greater than the specificheat and density of the gas used in air-inducting engines. Thanks tothis, a smaller mass of gas is required to absorb the heat of combustionin a cylinder in the airless engine than the mass of gas that isrequired to absorb an equal amount of combustion heat in a cylinder ofequal volume in an air-inducting engine at equal operating conditions.Therefore the volume of gas contained in the cylinder of the airlessengine at the beginning of gas compression can be substantially smallerthan the volume of gas contained in a cylinder of equal volume in theair-inducting engine at the beginning of gas compression in that engine.This permits to develop an airless engine and a method of its operationthat enables the airless engine to operate in overexpanded cycle withoutthe need to increase the volume relative to the volume of conventionalair-inducting engine of equal power.

In a piston-type internal combustion engine, the piston reciprocates inthe engine cylinder, thus varying the volume of the cylinder chambercontaining the gas participating in the engine cycle.

In a typical air-inducting engine, the volume of gas contained in thatcylinder chamber at the beginning of gas compression is approximatelyequal to the volume of the entire cylinder, and the compression andexpansion of that gas are about equal.

Consider an airless engine with a cylinder volume equal to the cylindervolume in the above air-inducting engine. In the airless engine of thepresent invention, the gas contained in the cylinder chamber at thebeginning of gas compression occupies only a fraction of the fullcylinder volume, and the gas compression takes up only a fraction of thepiston stroke, while the gas expansion takes up the entire pistonstroke. The clearance volume is reduced too, so that a desirable valueof compression ratio is retained. Reduction in the clearance volumeincreases the expansion ratio, which remains substantially greater thanthe compression ratio, thus improving the engine efficiency. An increasein efficiency is achieved without increase in cylinder volume. There isno reduction in power density.

Elimination of Throttling

A conventional, Otto cycle internal combustion engine uses air for itsoperation. Oxygen, contained in that air, is used to combust the fuel,while the remaining gas, which is mostly nitrogen, serves as a diluentabsorbing the heat and keeping the temperature in the cylinder withinacceptable limits. Throttling of the intake air is used to control itsflow.

In the airless engine, oxygen is supplied and controlled separately. Theairless engine uses its own exhaust as a diluent instead of nitrogen.That gas, which is a mixture of carbon dioxide and water vapor, isreused as a diluent gas in the following cycle. Oxygen and fuel areadded, and the resulting mixture is used to perform the combustioncycle. No air is inducted into the engine.

Some of the exhaust gas is in excess of the intake needs of the engineand is expelled from the engine system. The mass of the excess gas isequal to the mass of oxygen and fuel (and water, if any) added to theengine. It consists mostly of carbon dioxide mixed with a smallerfraction of water vapor. Water vapor is condensed and disposed of. Whatremains is carbon dioxide gas that is cooled to approximately constanttemperature and flows into a compressor that is part of the carboncapture system. That gas represents the carbon dioxide created incombustion.

The engine gas flow system is arranged so that the pressure at the inletto the compressor is equal to the pressure of the diluent gas flowinginto or retained in the engine. The mass of the newly created carbondioxide is proportional to the mass of fuel received into the engine.The compressor has constant displacement and it operates with a speedthat varies in proportion to the changes in the speed of the engine.

Since the compressor displacement is fixed, and the compressor inlet gastemperature is approximately constant, any change in the mass ofcompressor inlet flow per cycle must be associated with a proportionalchange in its pressure, which is equal to the pressure of the enginediluent gas. Therefore the mass of the diluent gas in the engineautomatically varies in proportion to changes in the fuel flow. Thesystem is inherently self-regulating, and the mass of the diluent gasautomatically changes in proportion to the changes in the mass flow ofthe fuel received into the engine. The gas-to-fuel ratio remainsconstant, and there is no need for throttling to control the flow of theinducted diluent gas. This reduces the pumping loss and contributes tobetter fuel efficiency.

Recovery of Lost Heat

An alternative to the above described concept is a concept, in whichthere is no outside cooling of the recirculated gas: The engine inductshot exhaust gas, which is cooled by an in-cylinder water injection. Inaddition to fuel and oxygen injectors, the engine is equipped with waterinjectors for direct injection of water into the cylinders. Fuel andoxygen are directly injected too. The exhaust gas is discharged fromeach cylinder into the exhaust manifold during the blowdown and theexhaust stroke and some of it comes back from the exhaust manifold intothe cylinder during the subsequent intake stroke and gets cooled bywater injection. The rest of the cycle is the same as in the systemdescribed above. The excess gas flows, through a discharge pipe andthrough a catalyst, into a carbon capture system. The mass of the excessgas is equal to the cumulative mass of fuel, oxygen and water injectedinto the engine.

Bringing back hot gas brings back to the cylinder some of the heat thatescaped from the cylinder previously. That heat adds to the heat ofcombustion and compensates for some of the heat that escaped withexhaust gas and with the coolant. The result is a net reduction in heatloss during the cycle.

Reducing Friction

A logical extension of the above-described four-stroke cycle concept isa concept, in which there is no intake of gas into the cylinder. Itinvolves retaining the combustion gas in the cylinder at the end of theexpansion stroke and discharging the excess gas during a part of thefollowing stroke. The cycle is completed in two piston strokes, insteadof four, which reduces the amount of friction work associated with thepiston rubbing against the walls of the cylinder. This improves theefficiency.

Varying Valve Timing

In some modes of the engine operation, there is a need for a substantialincrease in the power of the engine for a short period of time. Atypical example is an automobile engine during the vehicle acceleration,which requires a substantial increase in fuel delivery to the engine fora short period of time. In that case, to avoid excessive increase incylinder temperature, the amount of diluent gas should be increased too.

In the airless engine operating in overexpanding cycle, the amount ofdiluent gas inducted depends on the timing of the intake valve closure.The engine control system may include a variable valve timing control,which can be used to change the timing of closure of intake valve, atheavy engine load, so that the volume of gas contained in said cylinderchamber at the beginning of said gas compression is substantiallyincreased and greater amounts of said fuel and oxygen are injected intosaid cylinder chamber. In this way, the required peak power is achievedwith smaller engine displacement, whereby friction loss is reduced and,whereby the efficiency of said airless engine is improved.

Minimizing the Volume of Gas Storage

Internal combustion engines are frequently used to power transportationvehicles. The engine system of the present invention, when installed ina vehicle, requires an on-board gas-storage means for storage of carbondioxide, produced in combustion, until that gas can be removed forlonger term storage. In many cases, an on-board gas-storage means tostore oxygen used in combustion is needed too.

In transportation vehicles, space is limited and the volume of thestorage means for storing the carbon dioxide and oxygen should beminimized. The present invention offers a method of gas storage thatminimizes the volume of that storage. It involves providing a pluralityof gas containers, each capable of storing oxygen, at first, and storingcarbon dioxide later. Storing oxygen and carbon dioxide sequentially inthe same container minimizes the volume required.

Converting Carbon Dioxide and Water into Fuel

An attractive way to sequester the carbon dioxide, produced in theengine of the present invention, is to combine it with water in achemical reaction that produces hydrocarbon fuel. A conversion apparatusreceives carbon dioxide from the engine and uses it to producehydrocarbon fuel and oxygen, which are supplied back to the engine. NASAreceived a U.S. Pat. No. 9,528,192 for conversion of carbon dioxide intofuel, using sunlight as a source of energy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an airless engine system withcooled exhaust gas recirculation.

FIG. 2 is a schematic diagram illustrating a carbon capture system forthe airless engine system.

FIG. 3 is a pressure-volume diagram of the cycle for the airless engineof FIG. 1 operating with early intake valve closing.

FIG. 4 is a pressure-volume diagram of the cycle for the airless engineof FIG. 1 operating with late intake valve closing.

FIG. 5 illustrates pressure-volume diagrams of the cycle for the airlessengine of FIG. 1 operating with variable intake valve timing.

FIG. 6 is a schematic diagram illustrating an airless engine system withhot exhaust gas return or retention.

FIG. 7 is a schematic diagram illustrating a cylinder in an airlessengine with exhaust manifold integrated with the engine cylinder head.

FIG. 8 is a pressure-volume diagram for the airless engine of FIG. 6operating in four-stroke cycle with hot gas return.

FIG. 9 is a pressure-volume diagram for the airless engine of FIG. 6operating in two-stroke cycle with hot gas retention.

FIGS. 10A and 10B show an example of a gas storage container that can beselectively connected either to the oxygen-induction system, or to thecarbon capture system.

FIGS. 11A and 11B show an example of how a group of containers can besequentially discharged of oxygen and charged with carbon dioxide.

FIG. 12 is a schematic diagram illustrating sequestration of carbondioxide by converting it into fuel that is supplied back to the engine.

DESCRIPTION OF THE PREFERRED METHOD OF OPERATION

There are two methods for filling the engine cylinders with the diluentexhaust gas: gas recirculation and gas retention. The first methodinvolves recirculating the exhaust gas from the exhaust manifold intothe intake manifold. This is the preferred method of operation.

FIG. 1 schematically illustrates the concept of the airless engine withgas recirculation. That arrangement includes an engine 11 receiving fueland oxygen and a system of connecting pipes that form agas-recirculation conduit 12 connecting the engine intake manifold 13 tothe exhaust manifold 14. The gas-recirculation conduit 12 includes a gascooler 15 for cooling the recirculated gas. The engine control unit 16controls the cooling, to maintain the intake gas at sufficiently low,approximately constant temperature. There is no throttle at the inlet tothe intake manifold. The engine is unthrottled, and the intake manifoldpressure is always equal to the pressure in the gas-recirculationconduit. Oxygen and fuel are injected either into the intake flow, ordirectly into each cylinder.

Exhaust gas, expelled from each cylinder during each exhaust stroke, issplit into two fractions: the recirculated gas fraction and the excessgas fraction. The recirculated gas fraction flows from the engineexhaust manifold 14, via the gas-recirculation conduit 12, into theengine intake manifold 13 and is inducted back into each cylinder duringeach intake stroke. The excess gas fraction contains the gas that is inexcess of the intake needs of the engine. It flows through a catalyst 18into a carbon-capture system 17. The pressure of gas in the excess gasfraction is equal to the pressure in the recirculated gas fraction.

FIG. 2 is a schematic diagram of the carbon-capture system 17 (FIG. 1).The excess gas, expelled from the engine system, flows into a watercondenser 21, where it is cooled, and water vapor is condensed. Liquidwater collects in a water collector and may be disposed of periodically(not shown). The remaining gas is mostly carbon dioxide, and it flowsinto an engine-driven constant-displacement compressor 23. The pressureat the inlet to the compressor 23 is still equal to the pressure in theexcess gas fraction. That compressor pumps the gas, via a pressureregulator 24, into an electrically driven compressor 25, which iscapable to compress the gas to a supercritical pressure. Then, thehighly compressed carbon dioxide is deposited in a tank 26, where itcools and is stored as a liquid or a supercritical fluid.

The pressure regulator 24, at the inlet to the compressor 25, preventsthe compressor from being overloaded by excessive gas flow during suddenincrease in load and speed. At that time, the excessive flow istemporarily absorbed in a buffer tank 27. If the operation does notinvolve sudden increases in load and speed, the system may not includethe pressure regulator 24 and tank 27. In that case, the compressor 23pumps directly into the compressor 25.

In the engine of the present invention, the effective compression of thegas in the engine cylinder takes place only during a fraction of thepiston stroke. This is accomplished by proper timings of openings andclosings of the engine valves. Those timings are such that the volume ofgas contained in each engine cylinder, at the beginning of the gaseffective compression, is substantially smaller than the volume of gascontained in that cylinder at the end of combustion gas expansion. Theeffective compression is compression that begins with starting pressureequal to or higher than the intake pressure.

FIG. 3 illustrates a simplified pressure-volume diagram of one variantof the above preferred method. In the engine, the reciprocating motionof the pistons continuously varies the volume of the cylinder chamber ineach cylinder. At the beginning of the cycle, the intake valve openswhen the volume of the cylinder chamber is close to its minimum and,during the first part of the first volume-increasing stroke, from point31 to point 32, the recirculated gas is inducted from thegas-recirculation conduit. The intake valve closes early at point 32and, during the second part of the first volume-increasing stroke frompoint 32 to point 33, the inducted gas expands. Fuel and oxygen areinjected either into the gas-recirculation conduit, or directly into thecylinder chamber. In either case, a combustion mixture forms in thecylinder chamber.

During the first part of the first volume-decreasing stroke, from point33 to point 32, the gas is compressed, and its initial pressure isrestored. During the second part of the first volume-decreasing stroke,from point 32 to point 34, the effective compression of the gas takesplace. When the volume of the cylinder chamber is close to its minimumagain, the combustion mixture is ignited, and the initial combustionraises the pressure almost instantaneously (from point 34 to point 35).The combustion continues during the first part of the secondvolume-increasing stroke, from point 35 to point 36, followed byexpansion of combustion gas during the second part of the secondvolume-increasing stroke, from point 36 to point 37.

The exhaust valve opens when the volume of the cylinder chamber is closeto its maximum and, during the second volume-decreasing stroke frompoint 37 to point 31, there is a blowdown and the combustion gas isexpelled from the cylinder chamber into the gas-recirculation conduitand into the carbon-capture system. The exhaust valve closes when thevolume of the cylinder chamber is close to its minimum again. The gasexpelled into the gas-recirculation conduit is cooled in the gas cooler15 (FIG. 1) and flows back into the engine.

FIG. 4 illustrates a simplified pressure-volume diagram of anothervariant of the above preferred method. This one employs a late intakevalve closing. The intake valve opens when the volume of the cylinderchamber is close to its minimum and, during the first volume-increasingstroke from point 41 to point 42, the recirculated gas is inducted fromthe gas-recirculation conduit.

During the first part of the first volume-decreasing stroke, from point42 to point 43, some of the gas is pushed back into thegas-recirculation conduit. The intake valve closes late, at point 43,fuel and oxygen are injected, and a combustion mixture forms in thecylinder chamber. During the second part of the first volume-decreasingstroke, from point 43 to point 44, the effective compression of the gastakes place. When the volume of the cylinder chamber is close to itsminimum again, the combustion mixture is ignited, and the initialcombustion raises the pressure almost instantaneously (from point 44 topoint 45). Combustion continues during the first part of the secondvolume-increasing stroke, from point 45 to point 46, followed byexpansion of combustion gas during the second part of the secondvolume-increasing stroke, from point 46 to point 47.

The exhaust valve opens when the volume of the cylinder chamber is closeto its maximum and, during the second volume-decreasing stroke frompoint 47 to point 41, there is a blowdown and the combustion gas isexpelled from the cylinder chamber into the gas-recirculation conduitand into the carbon-capture system. The exhaust valve closes when thevolume of the cylinder chamber is close to its minimum again. The gasexpelled into the gas-recirculation conduit is cooled in the gas cooler15 (FIG. 1) and flows back into the engine.

Varying the timing of the intake valve closure permits varying thevolume of the inducted exhaust gas. For this, the engine must beequipped with a variable valve timing control. FIG. 5 illustrates twooverlapping pressure-volume diagrams of a cycle like the abovedescribed, in which a variable valve control leads to an increase inpeak power without an increase in engine volume.

The base cycle is: 51-52-53-54-55-56-57-51, the intake valve closes atpoint 53 and the volume of the recirculated diluent gas subject tocompression is 51-53. In the modified cycle, the timing of the intakevalve closure is changed to point 53′ and the volume of the diluent gasbecomes 51′-53′, which is greater than the original volume 51-53. Thispermits an increase in fuel and oxygen injected, and the cycle becomes:51′-52′-53′-54′-55′-56′-57′-51′. The power of the engine issubstantially increased, without an increase in the engine volume.Alternatively, this means that, with variable valve control, therequired peak power can be achieved with smaller engine displacement.Smaller engine has less friction and better efficiency.

Description of the First Alternative Method of Operation

This is a method, in which there is no outside cooling of the exhaustgas retained in the engine. The engine cylinders induct hot exhaust gas,which is cooled by an in-cylinder water injection. Such a concept isillustrated in FIG. 6. In addition to fuel and oxygen injectors, theengine is equipped with water injectors for direct injection of waterinto the cylinders. Fuel and oxygen are directly injected too. There isno transfer conduit, only a discharge pipe 62, and the engine has nointake valves and no intake manifold. There is only an exhaust system.

The exhaust gas is discharged from each cylinder into the exhaustmanifold 63 during the blowdown and the exhaust stroke and some of itcomes back into the cylinder during the subsequent intake stroke andgets cooled by water injection. The rest of the cycle is the same as inthe system of FIG. 1. The excess gas flows, through the discharge pipe62 and through a catalyst 64, into a carbon capture system 65. The massof the excess gas is equal to the cumulative mass of fuel, oxygen andwater injected into the engine. The carbon capture system isconceptually the same as illustrated in FIG. 2, but the capacity of thewater condenser must be sufficient to handle the additional water.

Gas exchange is greatly simplified: Elimination of intake valves freesadditional space in the cylinder head, and the exhaust manifold 71 isintegrated with the head, as illustrated in FIG. 7. There is only onetype of valve, the exhaust valve 72, which performs both the intake andexhaust functions. The valves, in each cylinder, remain open during theentire exhaust and intake period.

FIG. 8 illustrates a pressure-volume diagram of the above cycle. At thebeginning of the intake stroke, the exhaust valve 72 (FIG. 7) is fullyopen and, from point 81 to point 82, intake of hot gas takes place. Whenthe piston is in the vicinity of the BDC, the valve closes and coolingwater is injected, reducing the temperature and the pressure in thecylinder to point 88. The cooling water turns into steam that performsuseful work in the cycle. During the compression stroke, from point 88,via point 83, to point 84, gas compression takes place. The effectivecompression is 83-84, 84-85-86 is the combustion and expansion, and86-87 is continuation of the expansion. When the piston is in thevicinity of the BDC again, the valve opens and, from point 87 to point81, the gas is expelled from the cylinder. The expansion 85-86-87 ismuch greater than the effective compression 83-84. This is still anoverexpanded cycle. Advancing or retarding the timing of the valveclosure varies the quantity of the exhaust gas returned to the cylinderchamber.

Bringing back the hot gas brings back to the cylinder some of the heatthat escaped from the cylinder previously. That heat adds to the heat ofcombustion and compensates for some of the heat that escaped withexhaust gas and was lost to the coolant. The result is a net reductionin heat loss during the cycle and improvement in efficiency.

Description of the Second Alternative Method of Operation

This is a method that involves a two-stroke cycle, in which there is nointake of gas into the cylinder. There is only gas exhaust. Thevolume-decreasing stroke of the piston consists of two parts, the firstpart and the second part. The cycle involves discharging an excessfraction of combustion gas from the cylinder chamber during the firstpart of the volume-decreasing stroke, and retaining the remainingfraction of combustion gas in the cylinder. Cooling water is injectedand its evaporation cools the remaining gas. The rest of the cycle isthe same as in the system of FIG. 6.

The diagrams of the system are the same as in FIG. 6 and FIG. 7, but thevalve 72 (FIG. 7) serves only as exhaust valve. The excess gas flows,through the discharge pipe 62 (FIG. 6) and through a catalyst 64, into acarbon capture system 65. The mass of the excess gas is equal to thecumulative mass of fuel, oxygen and water injected into the engine. Thecarbon capture system is conceptually the same as illustrated in FIG. 2,but the capacity of the water condenser must be sufficient to handle theadditional water.

A pressure-volume diagram of such cycle is shown in FIG. 9. The valve 72(FIG. 7) closes at point 91 and, from point 91 to point 92, compressiontakes place. During that time, water, oxygen and fuel are injected intothe retained gas. The cooling water turns into steam that performsuseful work in the cycle. Steam formation in reduced cylinder volume, atpoint 91, cancels out pressure reduction associated with gas cooling.92-93-94 is the combustion and expansion and 94-95 is continuation ofthe expansion. At the end of the expansion, the valve opens and, frompoint 95 to point 91, the excess gas is expelled from the cylinder. Thenthe cycle is repeated during the next revolution. The expansion 93-94-95is much greater than the compression 91-92. This is still anoverexpanded cycle. Advancing or retarding the timing of the valveclosure varies the quantity of the exhaust gas retained in the cylinderchamber.

The cycle is completed in two piston strokes, instead of four, whichreduces the amount of friction work associated with the piston rubbingagainst the walls of the cylinder. This improves the efficiency.

Retaining the hot gas retains more heat in the cylinder. That heat addsto the heat of combustion and compensates for some of the heat thatescaped with exhaust gas and was lost to the coolant. The result is anet reduction in heat loss during the cycle and improvement inefficiency.

In both the first and the second alternative methods of operation, theengine system may be equipped with a variable valve timing system, whichpermits a temporary increase in power, as it was described in thedescription of the preferred method of operation.

DESCRIPTION OF THE METHOD TO MINIMIZE THE VOLUME OF GAS STORAGE

Internal combustion engines are frequently used to power transportationvehicles. The engine system of the present invention, when installed ina vehicle, requires an on-board gas-storage means for storage of carbondioxide, produced in combustion, until that gas can be removed forlonger term storage. In many cases, an on-board gas-storage means tostore oxygen used in combustion is needed too.

In transportation vehicles, space is limited and the volume of thestorage means for storing the carbon dioxide and oxygen should beminimized. The present invention offers a method of gas storage thatminimizes the volume of that storage. That method involves providing aplurality of gas containers, each capable of storing oxygen, at first,and storing carbon dioxide at a later time. Storing oxygen and carbondioxide sequentially in the same container minimizes the volumerequired.

More specifically, the above method involves providing anoxygen-induction system containing oxygen intended for engine combustionand a carbon-capture system containing carbon dioxide produced in enginecombustion, and it further involves providing a set of gas-storagecontainers comprising one empty gas-storage container and a plurality ofgas-storage containers filled with oxygen, wherein each gas-storagecontainer, in said set of gas-storage containers, has an inlet valve anda gas-flow distributor, wherein said inlet valve can selectively connectand disconnect the interior of said gas-storage container to and fromsaid gas-flow distributor, and wherein said gas-flow distributor can beselectively connected either to said oxygen-induction system or to saidcarbon-capture system, whereby the interior of said gas-storagecontainer can be selectively connected either to said oxygen inductionsystem or to said carbon-capture system,

FIGS. 10A and 10B show an example of a gas-storage container 101 thatcan be selectively connected either to an oxygen-induction system 102,or to a carbon-capture system 103. An inlet valve 104 is open only whengas-storage container 101 is active and gas is charged into ordischarged from that gas-storage container. When inlet valve 104 isopen, it connects gas-storage container 101 to a gas-flow distributor105, which contains a two-position rotary valve 106.

In FIG. 10A, inlet valve 104 is open. It shows rotary valve 106 in itsfirst position, in which it connects the interior of gas-storagecontainer 101 to oxygen-induction system 102. In this position of valve106, oxygen is discharged from gas-storage container 101 into theoxygen-induction system 102. FIG. 10B shows rotary valve 106 in itssecond position, in which it connects the interior of gas-storagecontainer 101 to carbon-capture system 103. In that position,gas-storage container 101 is charged with carbon dioxide fromcarbon-capture system 103.

FIGS. 11A and 11B illustrate an example of how five containers, 111 thru115, can be sequentially discharged of oxygen and charged with carbondioxide. Initially, container 111 is practically empty (internalpressure close to atmospheric pressure), and containers 112 to 115 arefilled with compressed oxygen.

In FIG. 11A, container 111 is connected to carbon-capture system 123 andis charged with carbon dioxide, while container 112 is connected tooxygen-induction system 122 and discharges oxygen into that system.Containers 113 to 115 remain inactive with their inlet valves closed.

When container 111 is fully charged with carbon dioxide and container112 is practically empty, the inlet valve in container 111 closes,trapping the carbon dioxide there. Then, the above process is repeatedwith containers 112 and 113. Container 112 is charged with carbondioxide, while container 113 discharges oxygen.

The above process is repeated sequentially with containers 113 and 114,and with containers 114 and 115. FIG. 11B illustrates the last stage,when container 114 is charged with carbon dioxide and container 115discharges its oxygen. After that, containers 111 thru 114 are filledwith carbon dioxide, container 115 is empty, and the storage system isready for unloading the collected carbon dioxide and to be rechargedwith fresh supply of oxygen.

Description of Fuel and Oxygen Regeneration

The engine of the present invention anticipates a fuel and oxygenregeneration process, in which the carbon dioxide, produced in theengine of the present invention, is to be used with water in a chemicalreaction in a conversion apparatus that produces hydrocarbon fuel andoxygen. Those fuel and oxygen are supplied back to the engine, wherethey convert into carbon dioxide and water again. That process of fuelregeneration can be repeated again and again indefinitely, as long assmall amounts of supplemental carbon dioxide and supplemental oxygen areadded to compensate for carbon dioxide lost to leakage and for excessoxygen used in the cycle. With good engineering, gas leakage can be verysmall, but it is not zero. Alternatively, fuel can be added, instead ofadding carbon dioxide.

FIG. 12 schematically illustrates the concept of sequestering the carbondioxide produced in engine combustion by converting it into fuel andoxygen that are used to power the engine. Engine system 121 producescarbon dioxide and discharges it via gas conduit 122 into carbon dioxidestorage 123. Conversion apparatus 124 receives carbon dioxide fromcarbon dioxide storage 123 via conduit 125, and it receives water from awater source 126 via conduit 127. Conversion apparatus 124 uses thecarbon dioxide and water to produce fuel and oxygen, and it dischargesthe produced fuel into fuel storage 128 via conduit 129, while theproduced oxygen is discharged into oxygen storage 1210 via conduit 1211.From fuel storage 128 and oxygen storage 1210, the fuel and oxygen aresupplied to engine system 121 via conduits 1212 and 1213, respectively.Supplemental carbon dioxide is supplied from carbon dioxide source 1214to carbon dioxide storage 123 via conduit 1215. Supplemental oxygen issupplied from oxygen source 1216 to oxygen storage 1210 via conduit1217. It is assumed that supplying the engine with fuel and oxygen takesplace at about the same time as discharge of carbon dioxide.

CONCLUSION, RAMIFICATIONS AND SCOPE

The engine system of the present invention can have a very positiveeffect on the environment. The engine receives no air from outsideatmosphere and discharges no gas into outside atmosphere. Therefore, incontrast to conventional internal combustion engines that dischargeexhaust gas into the atmosphere, the engine of the present inventiondischarges no harmful gas into the outside air, thus contributing tocleaner and healthier air environment. Since no carbon dioxide isreleased into the atmosphere, operation of the engine of the presentinvention has no adverse effect on the Earth climate.

The engine of the present invention can be considerably more efficientthan a conventional air-breathing engine. That is because the diluentgas used in the engine of the present invention is mostly carbon dioxideand water vapor, and the specific heat and density of that gas aresubstantially greater than the specific heat and density of the diluentgas used in air-inducting engines. This permits the engine of thepresent invention to operate in overexpanded cycle (Atkinson cycle),without increasing the size of the engine relative to the size ofconventional engine operating in Otto cycle. Atkinson cycle isconsiderably more efficient than the Otto cycle commonly used inconventional air-breathing engines.

The engine of the present invention needs no throttle to control themass of its diluent gas. The mass of the diluent gas in the enginevaries automatically in proportion to changes in the fuel flow. Thegas-to-fuel ratio remains constant, and there is no need for throttlingto control the flow of the inducted diluent gas. This reduces thepumping loss and further contributes to better fuel efficiency.

The engine of the present invention can operate with no outside coolingof the diluent gas. The engine can induct hot exhaust gas, which iscooled by an in-cylinder water injection. Bringing back hot gas bringsback to the cylinder some of the heat that escaped from the cylinderpreviously. That heat adds to the heat of combustion and compensates forsome of the heat that escaped with exhaust gas and with the coolant. Theresult is a net reduction in heat loss during the cycle. This is afurther improvement in the efficiency.

The engine of the present invention anticipates a fuel and oxygenregeneration process, in which the carbon dioxide, produced in theengine of the present invention, is to be used with water in a chemicalreaction in a conversion apparatus that produces hydrocarbon fuel andoxygen. Those fuel and oxygen are supplied back to the engine, wherethey convert into carbon dioxide and water again. That process of fueland oxygen regeneration can be repeated again and again indefinitely, aslong as small amounts of carbon dioxide and oxygen are added tocompensate for carbon dioxide lost to leakage and for the excess oxygenused in combustion. In that way, the engine fuel is repeatedlyregenerated and reused, and the engine operates in a carbon neutral modeof operation.

Although the description above contains much specificity, this shouldnot be construed as limiting the scope of the invention, but as merelyproviding illustrations of some of the presently preferred embodimentsof this invention. For example, it was assumed that the above describedengine and methods of operation use an injectable liquid hydrocarbonfuel. However, the concept of the present invention also applies toengines that use other types of fuels (for example gaseous fuel) thatmay be added to the recirculated gas before it enters the engine. Theconcept is not limited to reciprocating-piston-type engines. It alsoapplies to rotary-type internal combustion engines such as Wankel rotaryengine and to gas turbines.

Thus the scope of the invention should be determined by the appendedclaims and their legal equivalents, rather than by the examples given.

We claim:
 1. A method for operating and controlling an internalcombustion engine system, said method comprising the steps of: a)providing an airless internal combustion engine that inducts no air fromoutside atmosphere and exhausts no gas to outside atmosphere, saidengine including at least one cylinder, a cylinder chamber within saidat least one cylinder and a piston that can reciprocate in said at leastone cylinder varying volume of said cylinder chamber, said cylinderchamber containing diluent combustion gas that contains mostly carbondioxide and water vapor, said airless engine repeatedly receiving fueland oxygen into said cylinder chamber and repeatedly performing acombustion cycle that includes gas induction into said cylinder chamber,gas compression, combustion and gas expansion in said cylinder chamberand expulsion of combustion gas from said cylinder chamber, wherein saidcombustion gas expelled from said cylinder chamber contains mostlycarbon dioxide and water vapor, wherein said combustion gas expelledfrom said cylinder chamber is split into two fractions: a recirculatedgas fraction and an excess gas fraction, wherein specific heat anddensity of gas during combustion in said airless engine aresubstantially greater than specific heat and density of gas duringcombustion in an air-inducting engine, whereby a smaller mass of gas isrequired to absorb the heat of combustion in said at least one cylinderin said airless engine than the mass of gas required to absorb an equalamount of combustion heat in a cylinder of equal volume in anair-inducting engine with gas expansion equal to gas compression, saidat least one cylinder including at least one intake valve, at least oneexhaust valve and means for repeatedly performing openings and closingsof said at least one intake valve and said at least one exhaust valve,wherein timings of said openings and closings are such that the gascontained in said at least one cylinder at the beginning of said gaseffective compression occupies only a fraction of the full cylindervolume, and said gas compression takes up only a fraction of the pistonstroke, while said gas expansion takes up the entire piston stroke,whereby said gas expansion is substantially greater than said gascompression, and whereby said airless engine operates in overexpandedcycle, wherein the volume of gas contained in said at least one cylinderin said airless engine at the beginning of said gas compression issmaller than the volume of gas contained in said cylinder of equalvolume in said air-inducting engine at the beginning of gas compression,wherein the volume of gas contained in said at least one cylinder insaid airless engine at the end of said gas expansion is equal to thevolume of gas contained in said cylinder of equal volume in saidair-inducting engine at the end of gas expansion, and wherein clearancevolume in said at least one cylinder in said airless engine issubstantially smaller than clearance volume in said cylinder of equalvolume in said air-inducting engine, whereby said gas expansion in saidairless engine is substantially greater than gas expansion in saidair-inducting engine, whereby greater gas expansion contributes toimprovement in said airless engine thermodynamic cycle efficiency, andwhereby said improvement in said airless engine thermodynamic cycleefficiency is achieved without an increase in cylinder size, saidairless engine further including a gas-recirculation means for coolingand flowing said recirculated gas fraction from said at least oneexhaust valve to said at least one intake valve, said gas-recirculationmeans including a gas cooler means for cooling said recirculated gasfraction, (b) providing a carbon-capture means for receiving andhandling said excess gas fraction expelled from said cylinder chamber,said carbon-capture means comprising: (1) a water-condensation means forreceiving said excess gas fraction from said cylinder chamber,condensing water vapor contained in said excess gas fraction and coolingthe remaining gas, (2) a water-storage container, (3) a first compressorthat has a constant displacement and operates with a variable speed thatvaries in direct proportion to changes in the speed of said engine, (4)a second compressor, and (5) a carbon-dioxide-storage container, (c)providing a gas flow means for flowing gas between various parts of saidsystem, (d) providing a source of fuel and a source of oxygen, (e)providing a fuel-delivery means and an oxygen-delivery means fordelivering said fuel and said oxygen to said airless engine, (f)providing a control means for controlling the operation of said internalcombustion engine system in response to operator's demand and inaccordance with a control program incorporated in said control means,said control means including a manual implement for generating andvarying a control signal expressing said operator's demand, (g)operating said airless engine by repeatedly performing said combustioncycle that includes recirculated gas induction from saidgas-recirculation means into said cylinder chamber, fuel and oxygeninduction into said cylinder chamber, gas compression, combustion andexpansion in said cylinder chamber and expulsion of combustion gas fromsaid cylinder chamber, wherein said gas expansion is substantiallygreater than said gas compression, wherein said combustion gas expelledfrom said cylinder chamber is split into two fractions: a recirculatedgas fraction flowing into said gas-recirculation means and an excess gasfraction flowing into said carbon-capture means, wherein the pressure ofgas flowing into said gas-recirculation means is equal to the pressureof gas flowing into said carbon-capture means, wherein the mass of saidexcess gas fraction flowing into said carbon-capture means is equal tothe mass of said fuel and oxygen flowing into said airless engine, andwherein the mass of carbon dioxide contained in said excess gas fractionflowing into said carbon-capture means is proportional to the mass offuel inducted into said engine, (h) operating said carbon-capture meansby performing the steps of: (1) repeatedly receiving said excess gasfraction expelled from said cylinder chamber into saidwater-condensation means, condensing water vapor contained in saidexcess gas fraction, collecting water in said water-storage containerand cooling the remaining gas to a pre-determined temperature, whereinthe remaining gas is mostly carbon dioxide gas, (2) receiving saidcarbon dioxide gas from said water-condensation means into said firstcompressor, wherein the average mass of said carbon dioxide gas receivedinto said first compressor is proportional to said average mass of saidfuel received into said airless engine, wherein the gas pressure at theinlet to said first compressor varies in direct proportion to changes inthe mass of said fuel flowing into said airless engine, wherein the gaspressure at the inlet to said first compressor is equal to the pressureof said excess gas fraction, wherein the gas pressure at the inlet tosaid first compressor is equal to the pressure of said recirculated gasfraction, and wherein the mass of said recirculated gas flowing intosaid airless engine varies in direct proportion to changes in the massof said fuel flowing into said airless engine, whereby there is no needto use gas throttling to control the flow of said recirculated gas intosaid airless engine, whereby elimination of the pumping loss, associatedwith said gas throttling, contributes to improvement in said airlessengine efficiency, and whereby the gas-to-fuel ratio in said airlessengine remains constant, (3) compressing said carbon dioxide gas in saidfirst compressor and flowing compressed carbon dioxide gas into saidsecond compressor, (4) receiving said compressed carbon dioxide gas fromsaid first compressor into said second compressor, (5) furthercompressing said compressed carbon dioxide gas in said second compressorand discharging further compressed carbon dioxide gas into saidcarbon-dioxide-storage container, and (6) cooling and storing saidfurther compressed carbon dioxide gas in said carbon-dioxide-storagecontainer, wherein carbon dioxide is stored as a liquid or as asupercritical fluid, (i) controlling the operation of said internalcombustion engine system by manually varying said control signal,wherein said control means responds to the change in said control signalby performing the steps of: (1) varying the mass of said fuel receivedinto said cylinder chamber to satisfy said operator's demand for saidairless engine speed and power, (2) varying the mass of said oxygenreceived into said cylinder chamber to satisfy the conditions forefficient combustion of said fuel in accordance with said controlprogram incorporated in said control means, (3) varying other operatingfactors in said airless engine in accordance with said control programincorporated in said control means, said operating factors includingignition timing and injection timing, whereby, thanks to reduced volumeof gas contained in said at least one cylinder at the beginning of saidcompression and a proportional reduction in clearance volume in said atleast one cylinder, an increase in expansion ratio is achieved, whilethe compression ratio remains unchanged, whereby said increase inexpansion ratio is accomplished without an increase in volume of said atleast one cylinder, whereby said increase in expansion ratio improvesthe efficiency of said airless engine, whereby said improvement inefficiency of said airless engine is achieved without a reduction insaid engine power density, whereby, thanks to flowing said carbondioxide gas into a compressor that has a constant displacement andoperates with a speed that is proportional to the speed of said airlessengine, the mass flow of said recirculated gas varies in proportion tosaid mass flow of fuel into said airless engine, whereby no throttlingis needed to control the flow of said recirculated gas, wherebyelimination of throttling loss further contributes to improvedefficiency of said airless engine, and whereby gas-to-fuel ratio in saidairless engine remains constant regardless of changes in said engineload.
 2. The method of claim 1 wherein the step of operating saidairless engine includes the steps of: (1) opening said at least oneintake valve when the volume of said cylinder chamber is close to itsminimum, (2) inducting gas from said gas-recirculation means into saidcylinder chamber during the first part of said piston firstvolume-increasing stroke, (3) closing said at least one intake valve,(4) expanding said gas in said cylinder chamber during the second partof said piston first volume-increasing stroke, (5) receiving fuel andoxygen into said cylinder chamber, whereby a combustion mixture isformed in said cylinder chamber, (6) compressing said combustion mixturein said cylinder chamber during the first part of said piston firstvolume-decreasing stroke, whereby the initial pressure in said cylinderchamber is restored, (7) performing effective compression of saidcombustion mixture in said cylinder chamber during the second part ofsaid piston first volume-decreasing stroke, (8) igniting said combustionmixture when the volume of said cylinder chamber is close to itsminimum, (9) performing expansion and combustion of said combustionmixture during the first part of said piston second volume-increasingstroke, whereby said combustion mixture converts into combustion gascontaining carbon dioxide and water vapor, (10) expanding saidcombustion gas during the second part of said piston secondvolume-increasing stroke, (11) opening said at least one exhaust valvewhen the volume of said cylinder chamber is close to its maximum, (12)expelling said combustion gas from said cylinder chamber into saidgas-recirculation means and into said carbon-capture means during thesecond volume-decreasing stroke of said piston, wherein the gas pressurein said gas-recirculated means is equal to the gas pressure in saidcarbon-capture means, and wherein the mass of gas flowing into saidcarbon-capture means is equal to the mass of said fuel and oxygenflowing into said airless engine, (13) closing said at least one exhaustvalve when the volume of said cylinder chamber is close to its minimum,and (14) receiving said recirculated gas fraction of said combustion gasexpelled from said cylinder chamber into said gas-recirculation means,cooling it in said gas-recirculation means and flowing it from said atleast one exhaust valve to said at least one intake valve, whereby thevolume of gas contained in said cylinder chamber at the beginning ofsaid gas effective compression is determined by the timing of the earlyclosure of said at least one intake valve.
 3. The method of claim 1wherein the step of operating said airless engine includes the steps of:(1) opening said at least one intake valve when the volume of saidcylinder chamber is close to its minimum, (2) inducting gas from saidgas-recirculation means into said cylinder chamber during said pistonfirst volume-increasing stroke, (3) discharging said gas from saidcylinder chamber into said gas-recirculation means during the first partof said piston first volume-decreasing stroke, (4) closing said at leastone intake valve, (5) receiving fuel and oxygen into said cylinderchamber, whereby a combustion mixture is formed in said cylinderchamber, (6) performing compression of said combustion mixture in saidcylinder chamber during the second part of said piston firstvolume-decreasing stroke, (7) igniting said combustion mixture when thevolume of said cylinder chamber is close to its minimum, (8) performingexpansion and combustion of said combustion mixture during the firstpart of said piston second volume-increasing stroke, whereby saidcombustion mixture converts into combustion gas containing carbondioxide and water vapor, (9) expanding said combustion gas during thesecond part of said piston second volume-increasing stroke, (10) openingsaid at least one exhaust valve when the volume of said cylinder chamberis close to its maximum, (11) expelling said combustion gas from saidcylinder chamber into said gas-recirculation means and into said carboncapture means during the second volume-decreasing stroke of said piston,wherein the gas pressure in said gas-recirculated means is equal to thegas pressure in said carbon-capture means, and wherein the mass of gasflowing into said carbon-capture means is equal to the mass of said fueland oxygen flowing into said airless engine, (12) closing said at leastone exhaust valve when the volume of said cylinder chamber is close toits minimum, and (13) receiving said recirculated gas fraction of saidcombustion gas expelled from said cylinder chamber into saidgas-recirculation means, cooling it in said gas-recirculation means andflowing it from said at least one exhaust valve to said at least oneintake valve, whereby the volume of gas contained in said cylinderchamber at the beginning of said gas compression is determined by thetiming of the late closure of said at least one intake valve.
 4. Themethod of claim 1 wherein the step of providing said carbon-capturemeans includes the step of providing a compressor-protection systemincluding a pressure regulator installed before the inlet to said secondcompressor, and a short-term-storage reservoir installed before theinlet to said pressure regulator, wherein said pressure regulatorprevents excessive pressure at the inlet to said second compressor andwherein said short-term-storage reservoir temporarily absorbs excessiveflow of gas, whereby said second compressor is protected againsttemporary excessive increase in inlet pressure.
 5. The method of claim 1wherein said control system includes a variable valve timing control,said control system using said variable valve timing control to changethe timing of closure of said at least one intake valve, at heavy engineload, so that the volume of gas contained in said cylinder chamber atthe beginning of said gas effective compression is substantiallyincreased and greater amounts of said fuel and oxygen are injected intosaid cylinder chamber, wherein power of said airless engine issubstantially increased, whereby the required peak power is achievedwith smaller engine displacement, whereby friction loss is reduced and,whereby the efficiency of said airless engine is improved.
 6. The methodof claim 1 wherein said system includes an on-board gas-storage means,said gas-storage means performing a process of sequentially storingoxygen and carbon dioxide in the same volume of said gas-storage means,wherein storage of oxygen precedes storage of carbon dioxide, wherebythe required volume of said gas storage means is minimized.
 7. Themethod of claim 6, wherein said process of sequentially storing oxygenand carbon dioxide in the same volume comprises the steps of: (a)providing an oxygen-induction system containing oxygen intended for saidengine combustion and a carbon-capture system containing carbon dioxideproduced in said engine combustion, (b) providing a set of gas-storagecontainers comprising one empty gas-storage container and a plurality ofgas-storage containers filled with oxygen, wherein each gas-storagecontainer, in said set of gas-storage containers, has an inlet valve anda gas-flow distributor, wherein each said inlet valve can selectivelyconnect and disconnect the interior of said gas-storage container to andfrom said gas-flow distributor, and wherein said gas-flow distributorcan be selectively connected to said oxygen-induction system and to saidcarbon-capture system, whereby said interior of said gas-storagecontainer can be selectively connected to said oxygen-induction systemand to said carbon-capture system, (c) connecting the interior of saidempty gas-storage container to said carbon-capture system and connectingthe interior of one gas-storage container filled with oxygen to saidoxygen-induction system, (d) filling said empty gas-storage containerwith carbon dioxide and discharging oxygen from said one gas-storagecontainer connected to said oxygen-induction system until said onegas-storage container becomes a new empty gas-storage container, (e)connecting the interior of said new empty gas-storage container to saidcarbon-capture system and connecting the interior of another onegas-storage container filled with oxygen to said oxygen-inductionsystem, (f) filling said new empty gas-storage container with carbondioxide and discharging oxygen from said another one gas-storagecontainer connected to said oxygen-induction system until said anotherone gas-storage container becomes a new empty gas-storage container, and(g) continuing said process of sequentially storing oxygen and carbondioxide until said set of gas-storage containers comprises a pluralityof gas-storage containers filled with carbon dioxide, one emptygas-storage container, and no gas-storage containers filled with oxygen.8. The method of claim 1 wherein the step of providing the source offuel and the source of oxygen comprises the steps of: (a) providing acarbon dioxide storage means for storing carbon dioxide discharged fromsaid airless engine, (b) providing a conversion means for convertingcarbon dioxide and water into hydrocarbon fuel and oxygen, (c) providinga water source, (d) providing a fuel storage, (e) providing an oxygenstorage, (f) providing a supplemental carbon dioxide source, (g)providing a supplemental oxygen source (h) receiving carbon dioxide fromsaid airless engine into said carbon dioxide storage means, (i)receiving carbon dioxide from said carbon dioxide storage means intosaid conversion means, (j) receiving water from said water source intosaid conversion means, (k) converting said carbon dioxide and said waterin said conversion means into hydrocarbon fuel and oxygen, (l) receivingsaid hydrocarbon fuel from said conversion means into said fuel storage,(m) receiving said oxygen from said conversion means into said oxygenstorage, (n) receiving supplemental carbon dioxide from saidsupplemental carbon dioxide source into said carbon dioxide storagemeans, whereby said supplemental carbon dioxide compensates for gas lostto leakage, and (o) receiving supplemental oxygen from said supplementaloxygen source into said oxygen storage, whereby said supplemental oxygenprovides for the excess oxygen used in the combustion cycle, wherebysaid fuel storage serves as the source of fuel for said airless engine,whereby said oxygen storage serves as the source of oxygen for saidairless engine, whereby said airless engine is powered by hydrocarbonfuel produced by using carbon dioxide generated in said airless enginecombustion, whereby said airless engine fuel is repeatedly regeneratedand reused, and whereby said airless engine operates in a carbon neutralmode of operation.
 9. A method for operating and controlling an internalcombustion engine system, said method comprising the steps of: (a)providing an airless internal combustion engine that inducts no air fromoutside atmosphere and exhausts no gas to outside atmosphere, saidengine including at least one cylinder, a cylinder chamber within saidat least one cylinder and a piston that can reciprocate in said at leastone cylinder varying volume of said cylinder chamber, said cylinderchamber containing diluent combustion gas that contains mostly carbondioxide and water vapor, said airless engine repeatedly receiving fuel,oxygen and water into said cylinder chamber and repeatedly performing acombustion cycle that includes hot gas induction and water injectioninto said cylinder chamber, gas cooling, compression, combustion andexpansion in said cylinder chamber and expulsion of combustion gas fromsaid cylinder chamber into an exhaust manifold, wherein said combustiongas expelled from said cylinder chamber contains mostly carbon dioxideand water vapor, wherein said combustion gas expelled from said cylinderchamber is split into two fractions: a returned gas fraction and anexcess gas fraction, wherein said returned gas fraction is inducted fromsaid exhaust manifold back into said cylinder chamber and, wherein saidexcess gas fraction is expelled from said exhaust manifold, whereinspecific heat of gas during combustion in said airless engine issubstantially greater than specific heat of gas during combustion in anair-inducting engine, whereby a smaller mass of gas is required toabsorb the heat of combustion in said at least one cylinder in saidairless engine than the mass of gas required to absorb an equal amountof combustion heat in a cylinder of equal volume in an air-inductingengine with gas expansion equal to gas compression, said at least onecylinder including at least one exhaust valve and means for repeatedlyperforming openings and closings of said at least one exhaust valve,wherein timings of said openings and closings and cooling effect ofwater injection are such that that the gas contained in said at leastone cylinder at the beginning of said gas effective compression occupiesonly a fraction of the full cylinder volume, and said gas compressiontakes up only a fraction of the piston stroke, while said gas expansiontakes up the entire piston stroke, whereby said gas expansion issubstantially greater than said gas compression, and whereby saidairless engine operates in overexpanded cycle, wherein the volume of gascontained in said at least one cylinder in said airless engine at thebeginning of said effective gas compression is smaller than the volumeof gas contained in said cylinder of equal volume in said air-inductingengine at the beginning of gas compression, wherein the volume of gascontained in said at least one cylinder in said airless engine at theend of said gas expansion is equal to the volume of gas contained insaid cylinder of equal volume in said air-inducting engine at the end ofgas expansion, and wherein clearance volume in said at least onecylinder in said airless engine is substantially smaller than clearancevolume in said cylinder of equal volume in said air-inducting engine,whereby said gas expansion in said airless engine is substantiallygreater than gas expansion in said air-inducting engine, whereby greatergas expansion contributes to improvement in said airless enginethermodynamic cycle efficiency, and whereby said improvement in saidairless engine thermodynamic cycle efficiency is achieved without anincrease in cylinder size, (b) providing a carbon-capture means forreceiving and handling said excess gas fraction expelled from saidexhaust manifold, said carbon-capture means comprising: (1) awater-condensation means for receiving said excess gas fraction fromsaid exhaust manifold, condensing water vapor contained in said excessgas fraction and cooling the remaining gas, (2) a water-storagecontainer, (3) a first compressor that has a constant displacement andoperates with a variable speed that varies in direct proportion tochanges in the speed of said engine, (4) a second compressor, and (5) acarbon-dioxide-storage container, (c) providing a gas flow means forflowing gas between various parts of said system, (d) providing a sourceof fuel and a source of oxygen, (e) providing a fuel-delivery means andan oxygen-delivery means for delivering said fuel and said oxygen tosaid airless engine, (f) providing a source of water and awater-delivery means for delivering water to said airless engine, (g)providing a control means for controlling the operation of said internalcombustion engine system in response to operator's demand and inaccordance with a control program incorporated in said control means,said control means including a manual implement for generating andvarying a control signal expressing said operator's demand, (h)operating said airless engine by repeatedly performing said combustioncycle that includes the steps of: (1) inducting said return gas fractionfrom said exhaust manifold through said exhaust valve into said cylinderchamber during said piston first volume-increasing stroke, wherein thepressure of gas flowing into said cylinder chamber is equal to thepressure of gas in said exhaust manifold, (2) closing said exhaust valvewhen the volume of said cylinder chamber is close to its maximum, (3)receiving water into said cylinder chamber and cooling said returned gasfraction, whereby temperature and pressure in said cylinder chamber arereduced, (4) receiving fuel and oxygen into said cylinder chamber,whereby a combustion mixture is formed in said cylinder chamber, (5)compressing said combustion mixture in said cylinder chamber during thefirst part of said piston first volume-decreasing stroke, wherein theinitial pressure in said cylinder chamber is restored, (6) furthercompressing said combustion mixture in said cylinder chamber during thesecond part of said piston first volume-decreasing stroke, (7) ignitingsaid combustion mixture when the volume of said cylinder chamber isclose to its minimum, (8) performing expansion and combustion of saidcombustion mixture during the first part of said piston secondvolume-increasing stroke, whereby said combustion mixture converts intocombustion gas containing carbon dioxide and water vapor, (9) expandingsaid combustion gas during the second part of said piston secondvolume-increasing stroke, (10) opening said at least one exhaust valvewhen the volume of said cylinder chamber is close to its maximum again,(11) expelling said combustion gas from said cylinder chamber into saidexhaust manifold during the second volume-decreasing stroke of saidpiston, (12) expelling said excess gas fraction from said exhaustmanifold into said carbon capture-means, wherein the pressure of gasflowing into said carbon-capture means is equal to the pressure of gasin said exhaust manifold, wherein the mass of gas flowing into saidcarbon-capture means is equal to the mass of said fuel, oxygen and waterflowing into said airless engine, wherein the mass of carbon dioxidecontained in said excess gas fraction flowing into said carbon-capturemeans is proportional to the mass of fuel inducted into said engine, (i)operating said carbon capture means by performing the steps of: (1)repeatedly receiving said excess gas fraction expelled from said exhaustmanifold into said water-condensation means, condensing water vaporcontained in said excess gas fraction, collecting water in saidwater-storage container and cooling the remaining gas to apre-determined temperature, wherein the remaining gas is mostly carbondioxide gas, wherein pressure of excess gas received into said watercondensation means remains equal to gas pressure in said exhaustmanifold, and wherein the average mass of gas received into said watercondensation means is equal to the average mass of said fuel, oxygen andwater received into said airless engine, (2) receiving said carbondioxide gas from said water condensation means into said firstcompressor, wherein the average mass of said carbon dioxide gas receivedinto said first compressor is proportional to said average mass of saidfuel received into said airless engine, wherein the gas pressure at theinlet to said first compressor is equal to the pressure of said excessgas fraction, wherein the gas pressure at the inlet to said firstcompressor is equal to the gas pressure in said exhaust manifold, andwherein the mass of said returned gas flowing back into said cylinderchamber varies in direct proportion to changes in the mass of said fuelflowing into said airless engine, whereby the gas-to-fuel ratio in saidairless engine remains constant, (3) compressing said carbon dioxide gasin said first compressor and flowing compressed carbon dioxide gas intosaid second compressor, (4) receiving said compressed carbon dioxide gasfrom said first compressor into said second compressor, (5) furthercompressing said compressed carbon dioxide gas in said second compressorand, discharging further compressed carbon dioxide gas into saidcarbon-dioxide-storage container, and (6) cooling and storing saidfurther compressed carbon dioxide gas in said carbon-dioxide-storagecontainer, wherein carbon dioxide is stored as a liquid or as asupercritical fluid, (j) controlling the operation of said internalcombustion engine system by manually varying said control signal,wherein said control means responds to the change in said control signalby performing the steps of: (1) varying the mass of said fuel receivedinto said cylinder chamber to satisfy said operator's demand for saidairless engine speed and power, (2) varying the mass of said oxygenreceived into said cylinder chamber to satisfy the conditions forefficient combustion of said fuel in accordance with said controlprogram incorporated in said control means, (3) varying the mass of saidwater received into said cylinder chamber to satisfy the conditions forproper gas temperature in said cylinder chamber in accordance with saidcontrol program incorporated in said control means, (4) varying otheroperating factors in said airless engine in accordance with said controlprogram incorporated in said control means, said operating factorsincluding ignition timing and injection timing, whereby, thanks toreduced volume of gas contained in said at least one cylinder at thebeginning of said effective compression and a proportional reduction inclearance volume in said at least one cylinder, an increase in expansionratio is achieved, while the effective compression ratio remainsunchanged, whereby said increase in expansion ratio is accomplishedwithout an increase in the volume of said at least one cylinder, wherebysaid increase in expansion ratio leads to improvement in efficiency ofsaid airless engine, whereby said improvement in efficiency in saidairless engine is achieved without a reduction in said engine powerdensity, whereby, thanks to flowing said carbon dioxide gas into acompressor that has a constant displacement and operates with a speedthat is proportional to the speed of said airless engine, the mass ofsaid gas returned to said cylinder chamber varies in direct proportionto changes in the mass of said fuel flowing into said airless engine,whereby gas-to-fuel ratio in said airless engine remains constantregardless of changes in said engine load and there is no need forthrottling, whereby elimination of throttling leads to furtherimprovement in said airless engine efficiency, and whereby induction ofhot gas brings back to said cylinder chamber some of the heat thatescapes from said cylinder chamber in other engines, which adds to theheat of combustion, whereby there is a net reduction in heat loss duringthe cycle and whereby the efficiency of said airless engine is furtherimproved.
 10. The method of claim 9 wherein the step of providing saidcarbon-capture means includes the step of providing acompressor-protection system including a pressure regulator installedbefore the inlet to said second compressor, and a short-term-storagereservoir installed before the inlet to said pressure regulator, whereinsaid pressure regulator prevents excessive pressure at the inlet to saidsecond compressor and, wherein said short-term-storage reservoirtemporarily absorbs excessive flow of gas, whereby said secondcompressor is protected against temporary excessive increase in inletpressure.
 11. The method of claim 9 wherein said control system includesa variable valve timing control, said control system using said variablevalve timing control to change the timing of closure of said at leastone exhaust valve, at heavy engine load, so that the volume of gascontained in said cylinder chamber at the beginning of said gaseffective compression is substantially increased and greater amounts ofsaid fuel and oxygen are injected into said cylinder chamber, whereinpower of said airless engine is substantially increased, whereby therequired peak power is achieved with smaller engine displacement,whereby friction loss is reduced and, whereby the efficiency of saidairless engine is improved.
 12. The method of claim 9 wherein saidsystem includes an on-board gas-storage means, said gas-storage meansperforming a process of sequentially storing oxygen and carbon dioxidein the same volume of said gas-storage means, wherein storage of oxygenprecedes storage of carbon dioxide, whereby the required volume of saidgas storage means is minimized.
 13. The method of claim 12, wherein saidprocess of sequentially storing oxygen and carbon dioxide in the samevolume comprises the steps of: (a) providing an oxygen-induction systemcontaining oxygen intended for said engine combustion and acarbon-capture system containing carbon dioxide produced in said enginecombustion, (b) providing a set of gas-storage containers comprising oneempty gas-storage container and a plurality of gas-storage containersfilled with oxygen, wherein each gas-storage container, in said set ofgas-storage containers, has an inlet valve and a gas-flow distributor,wherein each said inlet valve can selectively connect and disconnect theinterior of said gas-storage container to and from said gas-flowdistributor, and wherein said gas-flow distributor can be selectivelyconnected to said oxygen-induction system and to said carbon-capturesystem, whereby said interior of said gas-storage container can beselectively connected to said oxygen-induction system and to saidcarbon-capture system, (c) connecting the interior of said emptygas-storage container to said carbon-capture system and connecting theinterior of one gas-storage container filled with oxygen to saidoxygen-induction system, (d) filling said empty gas-storage containerwith carbon dioxide and discharging oxygen from said one gas-storagecontainer connected to said oxygen-induction system until said onegas-storage container becomes a new empty gas-storage container, (e)connecting the interior of said new empty gas-storage container to saidcarbon-capture system and connecting the interior of another onegas-storage container filled with oxygen to said oxygen-inductionsystem, (f) filling said new empty gas-storage container with carbondioxide and discharging oxygen from said another one gas-storagecontainer connected to said oxygen-induction system until said anotherone gas-storage container becomes a new empty gas-storage container, and(g) continuing said process of sequentially storing oxygen and carbondioxide until said set of gas-storage containers comprises a pluralityof gas-storage containers filled with carbon dioxide, one emptygas-storage container, and no gas-storage containers filled with oxygen.14. The method of claim 9 wherein the step of providing the source offuel and the source of oxygen comprises the steps of: (a) providing acarbon dioxide storage means for storing carbon dioxide discharged fromsaid airless engine, (b) providing a conversion means for convertingcarbon dioxide and water into hydrocarbon fuel and oxygen, (c) providinga water source, (d) providing a fuel storage, (e) providing an oxygenstorage, (f) providing a supplemental carbon dioxide source, (g)providing a supplemental oxygen source (h) receiving carbon dioxide fromsaid airless engine into said carbon dioxide storage means, (i)receiving carbon dioxide from said carbon dioxide storage means intosaid conversion means, (j) receiving water from said water source intosaid conversion means, (k) converting said carbon dioxide and said waterin said conversion means into hydrocarbon fuel and oxygen, (l) receivingsaid hydrocarbon fuel from said conversion means into said fuel storage,(m) receiving said oxygen from said conversion means into said oxygenstorage, (n) receiving supplemental carbon dioxide from saidsupplemental carbon dioxide source into said carbon dioxide storagemeans, whereby said supplemental carbon dioxide compensates for gas lostto leakage, and (o) receiving supplemental oxygen from said supplementaloxygen source into said oxygen storage, whereby said supplemental oxygenprovides for the excess oxygen used in the combustion cycle, wherebysaid fuel storage serves as the source of fuel for said airless engine,whereby said oxygen storage serves as the source of oxygen for saidairless engine, whereby said airless engine is powered by hydrocarbonfuel produced by using carbon dioxide generated in said airless enginecombustion, whereby said airless engine fuel is repeatedly regeneratedand reused, and whereby said airless engine operates in a carbon neutralmode of operation.
 15. A method for operating and controlling aninternal combustion engine system, said method comprising the steps of:(a) providing an airless internal combustion engine that inducts no airfrom outside atmosphere and exhausts no gas to outside atmosphere, saidengine including at least one cylinder, a cylinder chamber within saidat least one cylinder and a piston that can reciprocate in said at leastone cylinder varying volume of said cylinder chamber, said cylinderchamber containing diluent combustion gas that contains mostly carbondioxide and water vapor, said airless engine repeatedly receiving fuel,oxygen and water into said cylinder chamber and repeatedly performing acombustion cycle that includes hot gas retention in said cylinderchamber, water injection into said cylinder chamber, gas cooling,compression, combustion and expansion in said cylinder chamber andexpulsion of excess gas fraction of said combustion gas from saidcylinder chamber into an exhaust manifold, wherein said excess gasfraction is expelled from said exhaust manifold, wherein said excess gasfraction contains mostly carbon dioxide and water vapor, whereinspecific heat of gas during combustion in said airless engine issubstantially greater than specific heat of gas during combustion in anair-inducting engine, whereby a smaller mass of gas is required toabsorb the heat of combustion in said at least one cylinder in saidairless engine than the mass of gas required to absorb an equal amountof combustion heat in a cylinder of equal volume in an air-inductingengine with gas expansion equal to gas compression, said at least onecylinder including at least one exhaust valve and means for repeatedlyperforming openings and closings of said at least one exhaust valve,wherein timings of said openings and closings and cooling effect ofwater injection are such that the gas contained in said at least onecylinder at the beginning of said gas effective compression occupiesonly a fraction of the full cylinder volume, and said gas compressiontakes up only a fraction of the piston stroke, while said gas expansiontakes up the entire piston stroke, whereby said gas expansion issubstantially greater than said gas compression, and whereby saidairless engine operates in overexpanded cycle, wherein the volume of gascontained in said at least one cylinder in said airless engine at thebeginning of said effective gas compression is smaller than the volumeof gas contained in said cylinder of equal volume in said air-inductingengine at the beginning of gas compression, wherein the volume of gascontained in said at least one cylinder in said airless engine at theend of said gas expansion is equal to the volume of gas contained insaid cylinder of equal volume in said air-inducting engine at the end ofgas expansion, and wherein clearance volume in said at least onecylinder in said airless engine is substantially smaller than clearancevolume in said cylinder of equal volume in said air-inducting engine,whereby said gas expansion in said airless engine is substantiallygreater than gas expansion in said air-inducting engine, whereby greatergas expansion contributes to improvement in said airless enginethermodynamic cycle efficiency, and whereby said improvement in saidairless engine thermodynamic cycle efficiency is achieved without anincrease in cylinder size, (b) providing a carbon-capture means forreceiving and handling said excess gas fraction expelled from saidexhaust manifold, said carbon-capture means comprising: (1) awater-condensation means for receiving said excess gas fraction fromsaid exhaust manifold, condensing water vapor contained in said excessgas fraction and cooling the remaining gas, wherein the remaining gas ismostly cooled carbon dioxide, (2) a water-storage container, (3) a firstcompressor that has a constant displacement and operates with a variablespeed that varies in direct proportion to changes in the speed of saidengine, (4) a second compressor, and (5) a carbon-dioxide-storagecontainer, (c) providing a gas flow means for flowing gas betweenvarious parts of said system, (d) providing a source of fuel and asource of oxygen, (e) providing a fuel-delivery means and anoxygen-delivery means for delivering said fuel and said oxygen to saidairless engine, (f) providing a source of water and a water-deliverymeans for delivering water to said airless engine, (g) providing acontrol means for controlling the operation of said internal combustionengine system in response to operator's demand and in accordance with acontrol program incorporated in said control means, said control meansincluding a manual implement for generating and varying a control signalexpressing said operator's demand, (h) operating said airless engine byrepeatedly performing said combustion cycle that includes the steps of:(1) closing said at least one exhaust valve at the end of the first partof said piston volume-decreasing stroke, (2) receiving water into saidcylinder chamber and cooling said hot gas retained in said cylinderchamber, whereby temperature in said cylinder chamber is reduced, (3)receiving fuel and oxygen into said cylinder chamber, whereby acombustion mixture is formed in said cylinder chamber, (4) compressingsaid combustion mixture in said cylinder chamber during the second partof said piston volume-decreasing stroke, (5) igniting said combustionmixture when the volume of said cylinder chamber is close to itsminimum, (6) performing expansion and combustion of said combustionmixture during the first part of said piston volume-increasing stroke,whereby said combustion mixture converts into combustion gas containingcarbon dioxide and water vapor, (7) expanding said combustion gas duringthe second part of said piston volume-increasing stroke, (8) openingsaid at least one exhaust valve when the volume of said cylinder chamberis close to its maximum, (9) expelling excess fraction of saidcombustion gas from said cylinder chamber into said exhaust manifoldduring the first part of said piston volume-decreasing stroke, (10)expelling said excess gas fraction from said exhaust manifold into saidcarbon capture-means, wherein the pressure of gas flowing into saidcarbon-capture means is equal to the pressure of gas in said exhaustmanifold, whereby said combustion cycle is completed in two pistonstrokes and whereby said airless engine is a two-stroke engine, whereinthe mass of gas flowing into said carbon-capture means is equal to themass of said fuel, oxygen and water flowing into said airless engine,wherein the mass of carbon dioxide contained in said excess gas fractionflowing into said carbon-capture means is proportional to the mass offuel inducted into said engine, (i) operating said carbon capture meansby performing the steps of: (1) repeatedly receiving said excess gasfraction expelled from said exhaust manifold into said watercondensation means, condensing water vapor contained in said excess gasfraction, collecting water in said water-storage container and coolingthe remaining gas to a pre-determined temperature, wherein the remaininggas is mostly carbon dioxide gas, wherein pressure of excess gasreceived into said water condensation means remains equal to gaspressure in said exhaust manifold, and wherein the average mass of gasreceived into said water condensation means is equal to the average massof said fuel, oxygen and water received into said airless engine, (2)receiving said carbon dioxide gas from said water condensation meansinto said first compressor, wherein the average mass of said carbondioxide gas received into said first compressor is proportional to saidaverage mass of said fuel received into said airless engine, wherein thegas pressure at the inlet to said first compressor is equal to thepressure of said excess gas fraction, wherein the gas pressure at theinlet to said first compressor is equal to the gas pressure in saidexhaust manifold, and wherein the mass of said gas retained in saidcylinder chamber varies in direct proportion to changes in the mass ofsaid fuel flowing into said airless engine, whereby the gas-to-fuelratio in said airless engine remains constant, (3) compressing saidcarbon dioxide gas in said first compressor and flowing compressedcarbon dioxide gas into said second compressor, (4) receiving saidcompressed carbon dioxide gas from said first compressor into saidsecond compressor, (5) further compressing said compressed carbondioxide gas in said second compressor and, discharging furthercompressed carbon dioxide gas into said carbon-dioxide-storagecontainer, and (6) cooling and storing said further compressed carbondioxide gas in said carbon-dioxide-storage container, wherein carbondioxide is stored as a liquid or as a supercritical fluid, (j)controlling the operation of said internal combustion engine system bymanually varying said control signal, wherein said control meansresponds to the change in said control signal by performing the stepsof: (1) varying the mass of said fuel received into said cylinderchamber to satisfy said operator's demand for said airless engine speedand power, (2) varying the mass of said oxygen received into saidcylinder chamber to satisfy the conditions for efficient combustion ofsaid fuel in accordance with said control program incorporated in saidcontrol means, (3) varying the mass of said water received into saidcylinder chamber to satisfy the conditions for proper gas temperature insaid cylinder chamber in accordance with said control programincorporated in said control means, (4) varying other operating factorsin said airless engine in accordance with said control programincorporated in said control means, said operating factors includingignition timing and injection timing, whereby, thanks to reduced volumeof gas contained in said at least one cylinder at the beginning of saidcompression and a proportional reduction in clearance volume in said atleast one cylinder, an increase in expansion ratio is achieved, whilethe compression ratio remains unchanged, whereby said increase inexpansion ratio is accomplished without an increase in the volume ofsaid at least one cylinder, whereby said increase in expansion ratioleads to improvement in efficiency of said airless engine, whereby saidimprovement in efficiency in said airless engine is achieved without areduction in said engine power density, whereby, thanks to flowing saidcarbon dioxide gas into a compressor that has a constant displacementand operates with a speed that is proportional to the speed of saidairless engine, the mass of said gas retained in said cylinder chambervaries in direct proportion to changes in the mass of said fuel flowinginto said airless engine, whereby gas-to-fuel ratio in said airlessengine remains constant regardless of changes in said engine load andthere is no need for throttling, whereby elimination of throttling leadsto further improvement in said airless engine efficiency, wherebyoperating in two-stroke cycle reduces the friction loss, which leads toimproved efficiency of said airless engine, and whereby retention of hotgas retains in said cylinder chamber some of the heat that escapes fromsaid cylinder chamber in other engines, which adds to the heat ofcombustion, whereby there is a net reduction in heat loss during thecycle and whereby the efficiency of said airless engine is furtherimproved.
 16. The method of claim 15 wherein the step of providing saidcarbon-capture means includes the step of providing acompressor-protection system including a pressure regulator installedbefore the inlet to said second compressor, and a short-term-storagereservoir installed before the inlet to said pressure regulator, whereinsaid pressure regulator prevents excessive pressure at the inlet to saidsecond compressor and, wherein said short-term-storage reservoirtemporarily absorbs excessive flow of gas, whereby said secondcompressor is protected against temporary excessive increase in inletpressure.
 17. The method of claim 15 wherein said control systemincludes a variable valve timing control, said control system using saidvariable valve timing control to change the timing of closure of said atleast one exhaust valve, at heavy engine load, so that the volume of gascontained in said cylinder chamber at the beginning of said gascompression is substantially increased and greater amounts of said fueland oxygen are injected into said cylinder chamber, wherein power ofsaid airless engine is substantially increased, whereby the requiredpeak power is achieved with smaller engine displacement, wherebyfriction loss is reduced, and whereby the efficiency of said airlessengine is improved.
 18. The method of claim 15 wherein said systemincludes an on-board gas-storage means, said gas-storage meansperforming a process of sequentially storing oxygen and carbon dioxidein the same volume of said gas-storage means, wherein storage of oxygenprecedes storage of carbon dioxide, whereby the required volume of saidgas storage means is minimized.
 19. The method of claim 18, wherein saidprocess of sequentially storing oxygen and carbon dioxide in the samevolume comprises the steps of: (a) providing an oxygen-induction systemcontaining oxygen intended for said engine combustion and acarbon-capture system containing carbon dioxide produced in said enginecombustion, (b) providing a set of gas-storage containers comprising oneempty gas-storage container and a plurality of gas-storage containersfilled with oxygen, wherein each gas-storage container, in said set ofgas-storage containers, has an inlet valve and a gas-flow distributor,wherein each said inlet valve can selectively connect and disconnect theinterior of said gas-storage container to and from said gas-flowdistributor, and wherein said gas-flow distributor can be selectivelyconnected to said oxygen-induction system and to said carbon-capturesystem, whereby said interior of said gas-storage container can beselectively connected to said oxygen-induction system and to saidcarbon-capture system, (c) connecting the interior of said emptygas-storage container to said carbon-capture system and connecting theinterior of one gas-storage container filled with oxygen to saidoxygen-induction system, (d) filling said empty gas-storage containerwith carbon dioxide and discharging oxygen from said one gas-storagecontainer connected to said oxygen-induction system until said onegas-storage container becomes a new empty gas-storage container, (e)connecting the interior of said new empty gas-storage container to saidcarbon-capture system and connecting the interior of another onegas-storage container filled with oxygen to said oxygen-inductionsystem, (f) filling said new empty gas-storage container with carbondioxide and discharging oxygen from said another one gas-storagecontainer connected to said oxygen-induction system until said anotherone gas-storage container becomes a new empty gas-storage container, and(g) continuing said process of sequentially storing oxygen and carbondioxide until said set of gas-storage containers comprises a pluralityof gas-storage containers filled with carbon dioxide, one emptygas-storage container, and no gas-storage containers filled with oxygen.20. The method of claim 15 wherein the step of providing the source offuel and the source of oxygen comprises the steps of: (a) providing acarbon dioxide storage means for storing carbon dioxide discharged fromsaid airless engine, (b) providing a conversion means for convertingcarbon dioxide and water into hydrocarbon fuel and oxygen, (c) providinga water source, (d) providing a fuel storage, (e) providing an oxygenstorage, (f) providing a supplemental carbon dioxide source, (g)providing a supplemental oxygen source (h) receiving carbon dioxide fromsaid airless engine into said carbon dioxide storage means, (i)receiving carbon dioxide from said carbon dioxide storage means intosaid conversion means, (j) receiving water from said water source intosaid conversion means, (k) converting said carbon dioxide and said waterin said conversion means into hydrocarbon fuel and oxygen, (l) receivingsaid hydrocarbon fuel from said conversion means into said fuel storage,(m) receiving said oxygen from said conversion means into said oxygenstorage, (n) receiving supplemental carbon dioxide from saidsupplemental carbon dioxide source into said carbon dioxide storagemeans, whereby said supplemental carbon dioxide compensates for gas lostto leakage, and (o) receiving supplemental oxygen from said supplementaloxygen source into said oxygen storage, whereby said supplemental oxygenprovides for the excess oxygen used in the combustion cycle, wherebysaid fuel storage serves as the source of fuel for said airless engine,whereby said oxygen storage serves as the source of oxygen for saidairless engine, and whereby said airless engine is powered byhydrocarbon fuel produced by using carbon dioxide generated in saidairless engine combustion, whereby said airless engine fuel isrepeatedly regenerated and reused, and whereby said airless engineoperates in a carbon neutral mode of operation.